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Off-hook delayed hotdial - SIP vs SCCP

Lester Wilson

Have a correctional facility customer who wants phones in certain parts of the jail that when they are left off-hook for 15 seconds to auto-dial their jail control center to a dedicated DN for off-hook auto-dials (i.e., officer takes phone off hook when there's an emergency and he can't stick around to talk on the phone). 

We tested this functionality on a SCCP IP Communicator soft phone during initial programming, but we're unable to make this happen on their 7821 SIP phones when we deployed Cisco UC to their jail facility.  

So in this case, I created a translation pattern of "blank", unchecked Urgent Priority, and put the DN I want the phone to hot dial to in Called Party Transform Mask.  Works fine when a SCCP phone stays off-hook without dialing and the call is connected to the jail control phone when the T302 interdigit timeout expires.  The SIP phone just hangs up after 15 seconds. 

I understand that SCCP and SIP phones handle dialing differently.  Just can't figure out a way to make it happen on a SIP phone.

Any advice would be appreciated. 



4 Replies 4

Vivek Batra

I think 7821 SIP phone doesn't send any off-hook signal to call manager unless all digits are dialed hence call manager can't invoke PLAR. It's different from Skinny which is tightly controlled by call manager who is aware about each and every state of phone.

Checking SIP dial rules might be of your interest;

Lester Wilson

So I'm almost there, but not quite what I want. 

Can make a SIP phone do PLAR – create a blank translation patter, uncheck Urgent Priority to make it wait 15 seconds when off hook before it calls whoever you want in the called party transformation mask, then create a blank SIP dial rule for PLAR and save it then apply that SIP dial rule to the phone.  Easy enough.  But once it’s off hook – they don’t get dial-tone and can’t dial anything else in the interim (expected behavior as it's now a PLAR phone). 

So it seems that for SCCP phones – the concept works great – go off-hook, get a dialtone for 15 seconds and you can dial whatever you want – otherwise if the phone is left off-hook for the duration of the T302 interdigit timer, the blank TP kicks in and it dials to whoever is on your called party transformation mask.  With SIP phones – it’s either PLAR or nothing.

Anyone been able to do what I'm looking to do with a SIP phone?  Or will I have to tell the customer they need to get some SCCP phones to make this work? 


Ashfaq Habeeb

A little late to the party, but I have Cisco SIP 8851 phones working Hotdial. 

I did all the configuration mentioned in the below link as per the SCCP phone.

After this configuration, I added a SIP dial plan given below, based on the below reference.

Add the SIP dial rule on the phone configuration page on both the source and destination. Other lines can be used to dial other numbers. 

Though this might not answer the delay before the off-hook call goes, its part of what you are looking for.  

Trying to get this to work with my SIP phones with not much success. Could you provide more details on how you got yours to work?

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